We present a systematic numerical study of a metal-dielectric-metal sandwich plasmonic structure for broadband resonant transmission at terahertz frequencies. The proposed structure consists of periodic slotted metallic arrays on both sides of a thin dielectric substrate and is demonstrated to exhibit a broad passband transmission response. Various design considerations have been investigated to exploit their influence on the transmission passband width and the center resonance frequency. The structure ensures a broadband transmission over a wide range of incident angles.